The present invention relates to a novel preventive and/or therapeutic for obesity.
A pharmaceutical preparation of the present invention has excellent preventive and/or therapeutic effects for obesity and is useful as a pharmaceutical.
Obesity is a risk factor of diseases such as diabetes mellitus, hypertonia, and heart disease, which threaten health of people in advanced countries. Obesity means physical conditions wherein adipose tissues have abnormally accumulated. Adipose tissues are special organs wherein surplus in vivo energies are stored as fat or triglyceride, and constructed of fibroblasts including adipocytes and their precursors, macrophages, blood vessel surrounding cells, blood cells, and the like.
Adipocytes are said to amount from ⅓ to ⅔ of cells which are present in adipose tissues and to accumulate fats or triglycerides therein. Adipocytes differentiate and mature through the process starting from mesenchymal multipotent stem cells, and growing into lipoblasts which have acquired a base as adipocytes, precursor adipocytes with no lipid droplets but having initial markers of adipocytes, immatured adipocytes containing lipid droplets, and finally into matured adipocytes containing a large quantity of accumulated fats. Adipocytes of adults suffering from slight obesity hypertrophically grow due to increase in the amount of accumulated triglyceride. Number of adipocytes increases as the degree of obesity becomes conspicuous. Therefore, decreasing the number of adipocytes by controlling differentiation and maturation or suppressing hypertrophia of matured adipocytes are expected to stop progress of obesity by suppressing the increase in the amount of accumulated fats, and to treat obesity. Control of in vivo adipocyte differentiation has been proven to undergo either positively or negatively according to a number of factors derived from environmental factors such as ingestion, exercise, and so on. As cytokines which control differentiation of adipocytes from adipocyte precursors, tumor necrosis factor-xcex1 (TNF-xcex1: Torti F. M. et al., Science, Vol. 229, p 867 (1985)), transforming growth factor-xcex2 (Ignotz R. A. et al., Proc. Natl. Acad. Sci. USA, Vol. 82, p 8530 (1985)), preadipocyte factor-1 (Pref-1: Smas C. M. et al., Cell, Vol. 73, p 725 (1993)), and the like have been reported. In addition, leptin, the translational product of an ob gene which has recently been cloned, has been reported to possibly decrease the intake amount and the weight of adipose tissues via central nerve system (Levin N. et al. Proc. Natl. Acad. Sci. USA, Vol. 93. P 1726, 1996).
Furthermore, intracerebral peptide-neuropeptide Y which exhibits a strong appetite stimulating effect and its receptor are gathering attention as materials for the development of an obesity suppressing pharmaceutical (Sainsburg A. et al, Diabetologia, Vol. 39, p353, 1996). These cytokines are expected to become a therapeutic agent for obesity due to their adipocyte depressing action on accumlation of fat. Clinical tests as an obesity therapeutic or preventive agent is ongoing on some of these cytokines such as leptin.
At present, one obesity therapeutic or preventive agent is commercially available in the USA under the Redux(trademark) (American Home Products Co.). Other drugs such as Meridia (Kunol Co.) and Xenical (Roche Co.) will be approved as an obesity treating agent or a fat absorption inhibitor in the USA. The treatments method using these pharmaceuticals, however, are not necessarily satisfactory in the effects and therapeutic results. Development of a new agent which is available exhibits for these pharmaceuticals higher curative effect and less side effect usable have been desired.
In view of the above circumstances, the present inventors have intensive investigated a substance which shows anti-obesity activity or obesity-curing activity, and as a result, found that stanniocalcin (STC: Olsen H. S. et al., Proc. Natl. Acad. Sci. USA, vol. 93, p 1792 (1996)) which is known as a protein controlling methabolism of minerals, exhibits adipogenesis inhibitory activity, or inhibitory activity of differentiation and/or maturation of adipocytes, which physiologic activity has not been expected of stanniocalcin at all in the past. Accordingly, the object of the present invention is to provide a preventive and/or therapeutical agent for obesity containing a novel substance as an effective ingredient. The present invention relates to a preventive and/or therapeutical agent for obesity, which contains stanniocalcin as an effective ingredient. The pharmaceutical preparation according to the present invention can exhibit excellent preventive and/or therapeutic agent effects for obesity and are useful as a pharmaceutical.
Stanniocalcin was discovered in fishes at first and was subsequently clarified to exist in mammals including humans. Then, cDNA of human embryo was isolated by the genetic engineering procedure on the basis of structural similarity. Human stanniocalcin can be obtained by expressing the resultant cDNA in a variety of cells using the genetic engineering technique.
It has been well known that stanniocalcin reduces a calcium level in vivo when given to fish, and also inhibits phosphate excretion to urine when administered to rats (Proc. Natl. Aca. Sci. USA., 93, 1792 (1996)). However, stanniocalcin has not been known to possess excellent preventive and therapeutic effects for obesity.
Stanniocalcin, or the effective ingredient according to the present invention, can be obtained by the method of Olsen H. S. et al. (Proc. Natl. Acad. Sci. USA, vol. 93, p 1792 (1996)). Specifically, the above-described literature reference or gene bank or the like can besearched to learn the sequence of cDNA of stanniocalcin, and based on the sequence information, stanniocalcin cDNA can be obtained using the PCR method etc. The stanniocalcin expression cell can be obtained by transfections of the expression vector into animal cells etc., the said expression vector is obtained by insertion of the resultant cDNA. Then, stanniocalcin can be obtained by cultivating the resultant stanniocalcin expression cells, followed by purification of the resultant culture solution by conventionally employed procedures. The adipogenesis inhibitory activity can be determined by estimating the suppression effects of adipogenesis induced by dexamethasone with retardation of triglyceride accumulation using mouse preadipocytic cell as a target according to the method of Kodama H. et al. (Journal of Cellular Physiology, Vol. 112, p83 (1982)).
Stanniocalcin, or the effective ingredient of the present invention, can be safely administered to human being and animals in the form of pharmaceutical compositions intended for use in the prevention and/or treatment of obesity. Stanniocalcin can be made into pharmaceutical preparations and administered either for orally or parenterally. Examples of the pharmaceutical composition include compositions for injection, compositions for dripping, suppositories, nasal agent, sublingual agent, percutaneous absorption agent, and the like. These pharmaceutical preparations are formulated according to known pharmaceutical preparation methods using pharmaceutically acceptable carriers, excipients, stabilizers, coloring matters, surfactants and other additives, and made into target preparations. In the case of compositions for injection, a pharmacologically effective amount of stanniocalcin, which is the effective ingredient of the present invention, may be mixed with pharmaceutically acceptable excipients/activators, such as amino acids, sugars, cellulose derivatives and other organic/inorganic compounds, which may be generally added to compositions for injection. If necessary, pH adjusting agents, buffer agents, stabilizers, solubilizing agents, etc. may be added to thereby make a variety of injectable solutions in accordance with the conventional procedures.
Administration thereof is normally done to human adults at a daily dose of 10 xcexcg to 10 mg/kg body weight, as divided in several times, either orally or parenterally. The particularly preferred dosage form is intravenous administration.